Courts will be swamped with legal challenges if there is an amnesty on Troubles-related crimes, critics have warned.

Furious victims’ families are vowing to fight tooth-and-nail to stop Attorney General John Larkin’s proposal to scrap inquests, inquiries and prosecutions into historic deaths and crimes becoming law.

And legal sources said any such an amnesty will open a Pandora’s Box of court challenges here and in Europe by relatives seeking the truth behind loved ones’ killings.

One said: “If legislation is brought in to make this law it would undoubtedly be open to challenge under Article 2 of the Human Rights Act – right to life.

“How this would work in practice is anyone’s guess.”

Former Police Ombudsman Dame Nuala O’Loan joined the Human Rights Commission and a leading lawyer in questioning whether any such proposal was legally workable.

She said: “To abandon prosecutions, inquests or inquiries into killings which took place before the Good Friday Agreement would constitute a wholesale violation of the UK’s legal obligations under domestic and international law.

“It would cause untold distress to bereaved families and seriously undermine prospects for building confidence in the administration of justice, in particular in cases where there is evidence of potential collusion between elements in the security services and paramilitaries.”

Marchers were shot in the street on Bloody Sunday

But Mr Larkin responded saying she was “mistaken” and the statute in question can’t apply to offences committed before the Good Friday Agreement.

John Corey, interim chairman of the Northern Ireland Human Rights Commission, said: “In dealing with the past there can be no deviation from the rule of law.”

The Northern Ireland Executive’s legal advisor’s comments come after he granted an inquest into the murders of two people by the loyalist Glenanne Gang, which included rogue members of the RUC and UDR, at the Step Inn bar in Keady, South Armagh in 1976.

He claimed his legal firm had “a consistent positive experience in dealing with the Attorney General generally regarding inquests, adding: “Against that background we find the announcement alarming.

“We find it inconsistent and a matter of deep concern.” The under-fire Attorney General claimed what he was proposing wasn’t an amnesty for paramilitaries or security forces who carried out killings.

But fuming victims’ relatives claimed any such move could extinguish their final hope of getting justice.

Mark Eakin, whose nine-year-old sister Catherine was killed in the 1972 Claudy bombing, claimed it was like telling America to give up hunting the 9/11 bombers.

He said: “He’d be better employed chasing after people in power who are withholding information no one can access.”

Kate Nash, whose brother William was killed by Paratroopers on Bloody Sunday in Derry in 1972, challenged US diplomat Dr Haass to reject any such suggestion.

Confronting the chief negotiator in Derry, Ms Nash made said: “What are they trying to do, draw a line under victims, draw a line under my brother? We are not going to let that happen.”

Mark Thompson, from Relatives of Justice, added: “We believe Mr Larkin is flying the kite for the British Government and for politicians.

“This is synchronised swimming in terms of the Haass talks. We say this is an amnesty today and next week and next month it will be amnesia and victims won’t allow that.”

British and Irish politicians were quick to distance themselves from Mr Larkin’s comments.

Put on the spot in the Commons by the DUP’s Nigel Dodds, Prime Minister David Cameron said: “The words of the Northern Ireland Attorney General are very much his own words.

“The second point I would make is that we are all democrats who believe in the rule of law, who believe in the independence of police and prosecuting authorities, and they should if they are able to, be able to bring cases.

“I think it’s rather dangerous to think that you can put some sort of block on that.”

However, Mr Larkin found an unlikely ally in former Northern Ireland Secretary Peter Hain – a politician he once took a court action againsy.

Mr Hain said: “He was right to put his head above the parapet because this issue is not going to go away.”

Likewise PSNI Chief Constable Matt Baggott appeared to support such a move to put more money in his strained policing budget.

He added: “Dealing with legacy issues continues to place significant pressure on our organisation and financial resources.”

However, Michael Gallagher, whose son Aiden was killed in the August 1998 Real IRA attack on Omagh, which claimed the lives of 29 people, including a woman pregnant with twins, said: “He is saying, ‘If you murder enough people, the Government will make a deal with you and you will eventually get off’.